Relieving machine



Jan., 27, 1948.

J. `MARTIN RELIEVING MACHINE Filed Sept. l2, 1945 6 Sheets-Sheet 1 i |.r l 1l l In.

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Jan. 27, 1948. J, MARTlN 2,435,046

vRELIEVING MACHINE Filed sept. 12, 1945 6 sheets-sheet 2 [N VEN TOR. 322171765 /WrLQ-z,

Jan. 27, 1948.

J. MAR'rlN RELIEVING MACHINE 6 Sheets-Sheet 3 Filed Sept. 12, 1945 NVENTOR.

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Jan. 27, 1948. J, MARTN 2,435,046

RELIEVING MACHINE Filed Sept. 12, 1945 .9Z @y im 6 Sheets-Sheet 4 1311.211948.' Y J, MAR-NN 2,435,046

RELIEVING MACHINE ,Filed-sept. 12, 194s e sheets-sheets l N V EN TOR. 3.5707752* Av/'Zin'. B Y

RELIEVING MQCHINE Filed Sept. 12, v1945 6 Sheets-Sheet L`EE1 BY A @.E. Mgyq Patented Jan. 27, 1948 RELIEVING MACHINE James Martin, Ferndale, Mich., assgnor to Michigan Tool Company, Detroit, Mich., a corporation of Delaware Application September 12, 1945, Serial No. 615,792

4 Claims. (Cl. 82--19) This invention relates generally to machine tools and more particularly to a substantially automatic machine for cutting the relief on the anks of the cutting teeth of a hob or similar tool.

As is well recognized, gear cutting hobs and similar tools are usually sharpened by grinding the front faces of the teeth. The intersection of this ground front face of each tooth with the flanks thereof provides the cutting edges of each tooth. Y Consequently, the precision and uniformity with which the anks of the teeth are generated largely controls the accuracy of the finished tool.

In order that the cutting edges of the hob will cut properly, it is essential that the flanks of each tooth be relieved or backed off to provide the proper relief or clearance behind the cutting edges.

Accordingly, it is the primary object -of the present invention to provide a simple, highly accurate machine for automatically cutting the flanks of the teeth of a hob to the desired form.

Another object of this invention is to provide for uniformly and evenly relieving hob teeth by arcuately moving the cutting tool as it engages said teeth. In order to achieve this result, the present invention contemplates a rocking table means for thus moving said tool as it engages said teeth.

Another object of the invention is to provide, in a machine of the type mentioned, simple means for accurately and automatically feeding the cutting tool. In order to accomplish this result, the

present invention contemplates means for positively locating the cutting tool during the entire cutting operation.

Another object of this invention is to provide novel and improved means for adjusting the cutting tool in preparation for the next cut simultaneously with the retraction of the cutting tool at the end of the hob lead so that upon return to its initial position it may immediately begin the next cut without further adjustment, In order to accomplish this result, the present invention contemplates automatic means which in no wise depends upon the ability or skill of the operator.

A further object of this invention is to provide a novel and improved construction of this type, requiring but minor adjustment to be adapted to apply relief to teeth of cutting hobs having a range of leads and varied numbers of flutes.

A still further object of the invention is to provide novel and improved means for automatically stopping the machine after the relieving opera- 2 tion is completed and which does not require th presence of the operator, I

Other objects of this invention will become apparent fromthe following specification, from the drawings relating thereto, andthe claims hereinafter set forth.

In the drawings, in which like numerals indicate like parts wherever indicated:

Figure 1 is a side elevational view of a relieving machine embodying the improvements of the present invention.

Figure 2 is a diagrammatic sketch showing the driving means which may be used to drive the y machine shown in Figure 1.

Figure 3 is a partially sectional plan view of the carriage and rocking table with other parts omitted.

Figure 4 is a plan view of the relieving machine shown in Figure 1 with the covering over the gearing and shafting removed.

Figure 5 is a partial perspective of the rear of the machine of my invention with the cam for rocking the toolholder shown.

Figure 6 is a perspective view showing a cutting hob mounted on the spindle preparatory to engagement with the cutting tool.

Figure 7 is a section on line 1--1 of Figure 3 to show the spring means for holding the rocking table against the rocking cam.

Figure 8 is a sectional view on line 8 8 of Figure 4 showing the means for retractlng and resetting the toolholder.

Fig. 9 is a section on line 9--9 of Figure 8 shovv-` ing the adjusting cam and ratchet means.

Figure 10 is a section on line Ill-I 0 of Figure 8 to show the pawl and supporting means therefor. Figure 11 is a diagrammatic sketch showing a pressure responsive system which may be used with a machine embodying my invention.

According to the present invention, a construction is provided whereby a hob, rotatably mounted, is engaged by a cutting tool which moves in a `direction parallel to the axis of rotation of said hob. Provision is made forrocking the cutting tool arcuately about an axis parallel to the axisl of rotation of the hob as the tool engages each tooth thereon. Upon reaching the end of the lead of the hob, the cutting tool is simultaneously reciprocated to a retracted position and reset for the next cut. 'A carriage then returns the tool to an initial or starting point where it is reciprocated out of the retracted position for engagement with the hob and the operation repeated.

Atthe termination of the operation, the Y cutting tool is returned to an initial or starting position and the driving motor is automatically stopped.

For a more detailed description of the invention reference may be had to the drawings, in which a base is generally indicated at I. Such base is a generally integral, hollow casting which forms a basefor` edetai'fpr sugpoigtinglftlge relu-,

lieving machine. AffdoorlZff permits access to ceritain of the apparatus, hereinafter described, 10 housed interiorly of said base.

The machine provides for rotatably supporting a hob 3, by means of a spindle 4 andatail' stock 5. Y Y

This spindle 4 is journaled; for. rotation. in ,a;.15.

suitable bearing 6 on an upper portion of base I and is adapted to receive oneendog arloarlil ,ii-porii which said hob 3 is mounted 'dringthe relieving operation In this manner, the rotation of spindle 4 is imparted to the workpiece. 20

| It rigidly lokginlgsalcltailstooktin predetermined 35;:

In order to accomplish reciprocation offtheecuttingttool; I liz-:parallel to theJ axisllof. rotationiof thelho);:durina-.thereIieyingI operation acarriage I 6 is provided to be reciprooated.rhmmeansof:feed-- 1Q` screw-:III:

Such carriagev I 6 istsupporteei.- byzshafttmeans., at each end thereof. Airone :endtsaidtcarriageis supportedionslidable.. shaft:v4 I'Bfbivlmeans' oisides I 9;;and fZIIrextendin'g; downwardlyirom saidffcarV 45b riage with alignedfropeningsZ-I and tNether-'ee throughthroughWhichasucnl slidable :shaftu I8: is permittedsto,v extends' AAtapered pinA 23 'passing through mating openings insidezl Q :andsshafti I 8fpointedaoutfthatfthis pin :23ffthreadablyengages anut 24 at its one extremity Wh-ichi-mayloeturned-t to Withdrawcthi's pin Whenit` is desired :to/remove either shaftslfo-scarriagai;

Atl'itsopposite end; thecarriage .depends-from 55 anfintegratedcarrieshafingeneally.indicated-alt-25:A Ear-.likecproiections.upwardlyzdrectedfrom fthe carriage;ferm` bearingst26dand 'l' 2.1 i with aligned`- openings. 28;.van'dl 29:. throughf'whioh 'shaft 125 extends;

-Inorder Iso-.provideformthis .reeiprocation of carri-age .I6;-;-by,1n`eans :ofrfeedscrew I 1, slidable shaft I ghas a; lead nutDspinnedatfS-Itlfiereto-forfthreadabIyuengaging;said..feed-.screw- It'g'willlbe observed that as-sucnfeedfscrewiisrotatedslraftf65 vided fbyibase l; 'lihus,^:A it '.is'duite. obvious that carriage fltwill beshited-LthereWith inasmuch? aslsaid ,carriage.isopinnedtosaidslidable .sha-ft;AAA

'Automatico reciprocation: isiv accomplished by 70 fmeans ofifdogs, 34; and'35 adjustably secixrgecttoA carriageel Bebyemeans oflT-bolts 36,`A slidablef in 'T- slotfofgsaidficarriage: and-:nutsf Saidifdegs: contact arm 39 of a limit switchvlI-vasleaclri reaches;itserespeotive; terminanlimit`l` of-travl, 75`

ent lsaeeemelisiedfes 4 effecting the reversal of a driving motor and driving mechanism later to be described. This, of course, effects the rotation of the feed screw and brings about the reciprocation of the carriage.

This reciprocation of carriage I6 is imparted to table 4| which is bracketed within the downwardly extending sides of the carriage. Such tafblegis p'krovidedtoarcuaitely'roci; cutting too1 I 5 about-an airis parallel to theuaxis ofrrotation of the workpiece as said tool traverses the lead on theiworkpiece.

.,Tahleiihas an annular opening 42 through which shaft I8 passes. The outer races of taperedgheaz'gingassembles and 44 are pressed into ltheaopposite egtremities of such annular opening and annularl'shoulders 45 and 46 on said races aloutthge: edgesqoi; `theboss through which the annular opening 'is formed. The inner races of saidfbearings mounted upon shaft I8 are separated by means of spacer 41. Thus, table 4I is piretallr-*Slmpertsde by; Said; shaft-i The; inner race heariesfgsbetsfshuleer Marsha@ In; andi meer# me @Firearms 45.,fahuts annales reieraelsalie heid-t-nrmi'yfiaplaiee by mit, 5U which threadably engages shaft I8. The outerf;

raffssoifsaidzbaer-.ieg1esenibliesfafreftelesconically rec Yedf Slseadampslledfm-reciprocateytherewith 'Rocking of table 4I is accomplishedasacam,

inafter described, I term cam 56 a rocking cami By, Installs-fof,- Compressione Spring; 51;4 4@figurer 7i.

whhhears 'urges a.. weesslrtfeeeeeerten .758.- Qff cerdas. @nieuwe i Oraal?! against resentment-59 a sereni? .t engaging@ against can@ lfrsatbt ,1r-rl operation; I Fiom] thcldescripton, itwiu retail *behielt will Inasmllh as l ta rods, @b91111- straft, I8?.

A p III:e reeiprocateswith. carriasallina ,direct parallelifethelaxisfoffrotataetha 119.19, ,it si duit@ ebreisl. camggmlist' also 7Joe i dl 0rd?? test1, 'i' andielllewer mit.. Qneeadtthisuaitisformd bylshaft sl'fwiucii; Jisjdrgi en by t later describe is telesoopicflly received by the Ahollow en d :1310i:

forirotationinf'pearingj@upwardly,directedirom baseis" i11- @heulen Spacers 5;! and; 5.2i: abutting; :aimizlefoneeme 4:,2;-1S formed-f. anular;` washers 5%k and 5&3

,bebclear 'thatfasthe cam is y e drivingnieansltovbe f., Suchlsllelfipisiourealed fer,.ro oo M1011 in, .bearings 62p* 21139353 .,uPFlaldly d irsted.

frorn'base I'jandrha's a hcill'loti` portion 6 4l with ,koyf

It will be observed that as shaft 6| is rotated, the integrated cam shaft is rotated by virtue of the association afforded by keys 66 and spline 68. It is pointed out, however, that the unit rotates rocking cam 56, keyed thereto at 11, in one direction only. One-way clutch 19 prevents reverse rotation of that portion of the unit to which said clutch is i'lxed when the driving mechanism is reversed, during reciprocation of carriage I6,V

in order to prevent injury to said cam.

By means of integral, upwardly-directed bearing 26, the carriage effects the reciprocation of cam follower 55. As such carriage travels in one direction, face 18 of such bearing forcibly presses annular spacer 19 against the face of annular collar 89 of clutch 19, compelling that portion of the integrated cam shaft 25 to'whichV shaft 61 is connected, to slidably move in a similar direction. When said carriage travels in an opposite direction, face 8| thereof forcibly presses annular spacer 82 against the face of shoulder 83 on shaft 69 to slidably move the slidable portion of the camshaft in a similar direction. Thus, cam 56'and follower 55 are constantly maintained in line.

:It will be appreciated that in order for cam 56 to be thus reciprocated, this slidable portion of camshaft 25 must slide in the hollow portion of Vshaft 6 I and clearance such as provided by depression 84 is required for clutch 19.

It will be further appreciated that cam 56 may beA conveniently changed by removing bolt 15 and withdrawing shaft 14 from the end of shaft 69, making said cam accessible for removal.

Up to this point the driving means has been referred to, but not described. In order to provide for the rotation of spindle 4, feed screw I1 and cam 56 in timed relationship, a suitable prime vmover in the form of electric motor-85 is supported at a lower rear part of base I. Electric current may be supplied from a convenient source to be controlled by means of start button 86 and stop button 81. Such motor 85 drives motor shaft 88, pulley 89, continuouso belt 99, double pulley 9|, continuous belt 92, pulley 93, and shaft 94 with worm 95 thereon. Worm 95 meshes worm gear 96 which drives shaft 91, gear 98 and gear train 99, |99, |9|, to drive shaft 6| of integrated camshaft 25 and thus cam 55. Gear 98 on shaft 91 meshes gear |92, driving shaft |93 and gear |94. Such gear |94 meshes gear |95, driving spindle 4 and gear train |96, |91, |98 to drive feed screw |1.

Gears |99 and |91 may be changed to adapt the machine for variation in the number of flutes appearing on the hob or the lead thereof. It is quite obvious that upon replacing said gear with others having a greater or lesser number of teeth, their respective gear train will be affected, affecting in turn, the timed relationship with which camshaft 25 and feed screw I1 rotate with respect to spindle 4. The use of this simple expedient permits a relieving machine of my invention to be adapted for applying relief on teeth of hobs having varied leads and numbers of flutes.

It is lto be noted that change gears |99 and |91 rotate upon shafts |99and I |9 respectively. Provision is made for varying the position of said shafts to accommodate the gear thereon in order that such gear may properly mesh in its respective gear train.

Upon reaching the end of the lead of the hob, the cutting tool is retracted out of engagement therewith and simultaneously reset for a new cut. It is then' returned to its starting position by carriage I6, as previously described, when vsaid tool is protracted into engagement with the hob and a new cutis begun.

In order to accomplish this reciprocation and resetting of the cutting tool, a tool support I|| is slidably mounted upon machined surface ||2 and slideway ||3 of rocking table 4|. A cylinder ||4, containing pressure actuated piston |I5, is anchored to depend from said tool support. This cylinder is provided with caps ||6 and |I1. Piston rod |I8, attached to piston ||5 for reciprocation therewith, extends through said cap |I6. A bolt ||9 is permitted to extend through mating openings provided by such piston and piston rod to threadably engage a tapped opening |29 in yoke I2 l, anchoring said yoke to the adjacent abutting end of piston rod I8. This yoke is slidably supported in slots |22 and |23 in the downwardly-directed sides |24 and |25, respectively, of table 4|. Such yoke provides aligned openings |26 and |21 through which shaft |28, rotatably supporting ratchets |29 and |39 and reset cam |3|, is permitted to extend. This shaft is secured in said openings by a shoulder |32 which abuts face |33 of said yoke and nut |34 threadably engaging said shaft at its opposite end to abut face |35 of the yoke. The ratchets with the reset cam therebetween occupy the space between arms |36 and |31 of the yoke and are integrally connected to shaft |28 by means of an elongated key |38 in such manner that the entire unit may be rotated by the ratchets.

This rotation is accomplished by a pawl |39 which engages the serrations |49 of the ratchets. `-Such pawl is pinned at |4| to shaft |42 which is supported in sides |24 and |25 of tablev 4|. The pawl is held in line with the ratchets by means of annular spacer |43 surrounding shaft |42 and torsion spring |44, which spring forcibly holds the pawl in engagement with the serrations of the ratchets. End |45 and end |46 of such spring enter drilled openings in the pawl and annular collar |41, pinned at |48 to the shaft |42, for thus forcibly holding the pawl.

A follower |49 is anchored to depend from the tool support by bolts |59. Such follower has a rounded tip |5| which is forcibly caused to engage the surface of reset cam I3| by means of compression spring |52 pressing upon face |53 of the follower. This compression spring is retained within an annular opening |54 provided in table 4| by a screw |55 which is threadably received in a tapped portion of said opening. It will be apparent that the force with which such spring bears upon the face of the follower may be varied by means of screw |55.

It will now be observed that as chamber |56 of the cylinder is pressurized to move the piston in a direction away from hob 3, the ratchets and cam will similarly move and this movement will eifect the rotation of said ratchets and cam by virtue of the engagement of the pawl with the serrations of said ratchets. Simultaneously spring |52, pressing upon follower |49 retracts tool slide Ill, keeping the tip of such follower in contact with the reset cam. However, the net retraction of the tool slide is the distance travelled by the piston less that recovered by the rotation of the cam as it will be clear that the retraction of the tool slide is retarded by the rotation of such cam, Therefore, it may be said the cutting tool is simultaneously retracted and reset for the next cut. v Y

The movement of piston H5 is accurately controlled by means of bolt |51 threadably received im aatapp'ed opening; ofcap; I -|-'I. ot` cylinderV H4: Such holtfprovidesf a: stop=whicharrests the? re.-k ciprocating movement of piston ||5 and. may be turnedgtoxincreasefor i decrease the extent ofsuch reciprox/ation.V

Aftencarriage Irreturns the tool support, I I I titsrinitial positiomehamber |5801e the cylinder isf-pressurized; moving; the; piston in a Y 4direction toward thefhobi It?` is: to; be noted` that when movementf occurs in .this direction; thefreset 'cam 10. is-.-n0t:rotatedi as the-serrations ofthe ratchetsslide` onf` the; inclined surface- |591` of` the pawl andcthatsncln movement. .electsfmovement of' the tool slidezimaesimilar-'direction 'due-to the contact betweenithe'rcamrand follower; thus` compressing- 15 spring; I5-2.. Itffisfalso pointed-outthat the cam is locked;y by; means-f ofthe: pawl and ratchets against: further;Y rotation until' the next recipro-V catngmovementoccurs.. It isiobvious that as the tool; supporti extentsol` suchiprotractionequals .that ofthe pistomibutin'viemofthefaet :it wasznot retractedany eqnalgamonnt; thex cutting. tool will be closer to thefhob t'liambeforea-retractionand :thuswill be in Positionfdcfv a new cut:

When this'resetzcamecompletes"one revolution; theirelievinge. operati-on isfcomplete-iand pin ISI! positionedsatfan;endfofrshaftz |28 to be rotated. thereblas saidshaftis rotatedby the ratchets I 29; andi I lfcontacts-switch I ELI (Figure 1). which 30 eiectst the lrstopping; of.; thee driving -motor upon return of the carriage tofitsiinitialf position.

Automatic' recprocatiom of; thee tool! carriage intceI ande` out? ofai retracted; position1 isY` accomf pli'sheellby meansnf the-previouslyrdescribedz'dogsa 35: Msandifanct-lmiti switch 4B.- In addition to. reversing?,the'directiornoffrotation ofi driving-motor-83i.suoli.liinitfswitchactuates-fasolenoidvalve |6215 as itlis: contacted; byr said dogs: This valveshiftsraepston I BiirsaidwalverW-hieh alternately 40..c

pressurizesxcliambersd 5&1and I 58: of cylinden'l I 4f for; reciprcoat-ing.the:l pistocnrA as, .ldescribedi 'Ihestoolsupport II: provides sa machined sur?r face |64 and slideWayr-Iruporr which atool slide |Bisfslidablyfmountedz; Such-f slide hascgroove I 65|' zthereiniwhijchaisxpartlycovered byyplates= I 68;. an@ I 69 in; suchemanner.r`v as f toi retain T-'nut |10# when-such pla-tes are: secured torthesslide by rb oltsf I 'I I.' Afitoolholderrl S123 is; rigidly-mounted onrthei tool; slide: byfmeanszfof: boltss I 13; Said; bolts;A exe 50 tendrthrouglf matingJ openings in;- capi |74?- and.. toolholder; |2f5topbertlireadablyareceived by the-f Tenut: I Maand-f upon being: tightened .positively-r hold; the;ft0o1holderfon: the toolesl-ide; Capi: I '|2527 coversafslotz` IISfinfwhich the cuttngtool |5is':55 retained by means ot boltssITSrwhi-chare thread-tl ablyqreceivedgby; T-nuts f| I1 ipositionedin; 'Vf-slots In: ordenfto; initially. position-1 the cutt'urigrftnoLI thisstcot .sli-de Ymap-.floecslidalulyrrrmuzed im a, i direc: 60 tion perpendicular` rtovthezaxisoffirotation" of ith'e hobibyLmeansfof feed screw I Such :feedscrew is; journalecl: for rotationrin a' suitable bearing. 1 |8.I ianchored toz-onefend-:otfthetftool support.V A

leadfnuti; I 82 pressed lirnzoffop,eningcl t3` of the; too'lA :65a:

slide threadablyfengageszsuch;'feed 4l'screW andzit Q Will-f, be fappreciated that i as i such; feed screwA is z rotated;v the tool -slide- Will-fsh-ift. A- conveniently accessible handwheelfiI 81|einteg-rally.connectedV to,` the ffeedscrevr; provi-desr-ffor1rotating thessaine.:

After; the.` cutting tool-isf;thusinitially posi.r tioned,it, may;loe-locked--positivelyfand securely in.: position by means of a, set-screw-I85-Whichfpree ven-ts. further mtation of;tl1e hanlwheel. n

Innr'derato .accomplish thefreciprocation:ofiathe: 75

is: protracted toward' the hob',V the ggf tool support into :andzout .of-v engagementiwith the hob asdescribedfapneumatie system.13.proviclediiy FigureY 11 shows -thesystemwithgthe cutting toolf positioned. to engage1thehob; vAspreviously exe; is' a isolenoid; valve actuated by. limit switch. upon contact by dogsg-34 andi 35ron the-carriage I6.. Thus; as shown in'Figurek 11,.` pneumatic .pressure'eis supplied hysupplyf lirre. 86.; to ports |81 and |88iand.- upon contact bydog-:34; the limit switchreifectsA shiftingrof piston IBS-byi means of solenoid? lvclosingsexhaust-,port `|90 and openingf port |81 to.-p'ortv ISI; line :|92,:port1v |93 and chamber |58 of cylinder II4 -protraoting the cutting; tool into engagement withi the? heb:A

Simultaneously, port lfis closedtoport |94.v while, exhaust port |95 is open thereto to per-l mit air exhausted fro chamher I 56 of 'said-rcyline der to esca-pe' by: wayof ,port' |96; line. Illi'l` and port |94 and; thence to. 'the atmosphere n through? said exhaust-port; s 4

When clog-v` 35 contacts'said: limit f'switch, sole-fnoid valve ISS-f causes piston L |63" to shift again;y opening port ItsV to port- |94= and close'exhaustiv port-|95 thereto. At the sametmaport |81isf' closed to port |9I While exhaust port |90 is open'- thereto, andpiston II 5 moves` avvayfA fromfthe heb,4 permitting the' compression spring I5 2: to? effect retraction of the cutting-tool.:

While Ihave shown. and -described a pneumatic system for effectingv reciprocation.- of piston: |55, it will* be apparent` to f those f skilled;l in f' the: art that suehreciprooationf might'wellf beaccom:hr plished -by hydraulic or f mechanicalmeans. andiA it is not-.intended.that the invention. be?. thus; limited.

Ityvill bec-clearrfrom vthe Yforegoingfdescription: that .the relieving machinefshown in `the :draw-- ings and described yalcove has been illustrated and; described: in rather" specific. detail.` Obviouslm. many modifications, changes; and? departures: from the abovedescribed construction :mayA be'.t made Without departingfromA the generic.spirit4 and scope'of the invention asfset frthninzfther subjoined claims.

What'is claimed is:

1. In a hoh.- tooth .flankrelieving" machine;U aTA base, a -reciprocable toolfsupportfmountedthereoni for mounting a"toolholder` for movement` intoy and out of aretractedposition; aicar'n follower." depending from saidtoolsupport;` a-'releasabla compression spring tomove' said tool supp'ort and `E cutting tool thereon to airetra-ctedposition; ai' pressure responsive piston for releasing" said' spring and compacting thesanie .upon' vretuniihg thetool support from a retracted position-:airotating ratchet and cam integrally fsecured'i to' "af shaft operatively f associated.' with fsaid pressure 2'! responsivey piston; said foam `follower: engaging'fthe surfaceZ of said cam'continuously to simultaneiy ously with the retractingj movement i reset" the cuttingv tool for.7 the next cut;v said:- ratchet en:- gagingja pawl causingfsaidiratchetand camito be rotated and" locking- A the cutting' tool.y :.inresetty position, and means f for, automaticallyactuating? said pressure responsive: means;r

2. In va hob tooth l. flank relievingmachinaf :a base; a reciprocable tool support mounted' thereon'.;

for supporting-a toolholderffor'movement fromif and to a' retracted position, a'camifoll'owerfde l, pending from said tool "support, areleasable'fcome.-

pression spring to move said tool support?y and-l cuttingftool thereon to affretractedipositiomaa, pressure" TBSDOUSV@ Diston.;fort relasingifsaidf' spring and compactingfthesameuponxeturrngff the, tool support v.from a fretractedzpositionsa re-1% ciprocable, integral cam and ratchet operatively associated with said pressure responsive piston, said cam follower engaging the surface of said cam to simultaneously with the retracting movement reset the cutting tool for the next cut, said ratchet engaging a pawl causing the cam to be rotated and locking the cutting tool in reset position, and means for automatically actuating said pressure responsive means.

3. In a hob tooth ank relieving machine, a base, a reciprocable tool support mounted thereon for mounting a toolholder for reciprocation into and out of a retracted position, said toolholder adapted to retain a cutting tool, a cam follower depending from said tool support, compression spring means to move said tool support and cutting tool thereon to a retracted position, pressure responsive means for releasing said spring means and compacting the same upon returning said cutting tool from the retracted position, an integral cam and ratchet means operatively associated with said pressure responsive means, said cam follower engaging the surface of said cam to simultaneously with the retracting movement reset the tool support and cutting tool thereon for the next cut, said ratchets engaging a pawl for locking the tool support in reset position, and means for automatically actuating said pressure responsive means.

4. In a machine for applying relief to the flanks of the teeth of a hob, a base, a tool support slidably mounted on said base for mounting a toolholder for movement from and to a retracted position, said toolholder adapted to retain l0 a cutting tool therein, spring means adapted to be released to move said support to a retracted position, automatic pressure responsive means to release said spring means and compress said spring means upon returning said support from a retracted position, rotating cam means activated by said fluid responsive means to reset said cutting tool for the next cut, an electric switch adapted to be contacted to stop the machine, a pin operatively connected to said cam for contacting said switch after one revolution of said cam, and means for operating said fluid responsive means.

JAMES MARTIN.

REFERENCES CITED The following references are of record 1n the le of this patent:

UNITED STATES PATENTS Number Name Date 1,865,528 Lorelg July 5, 1932 1,950,039 Smith Mar. 6, 1934 2,317,522 Curtis Apr. 27, 1943 1,429,616 Muller Sept. 19, 1922 1,778,769 Olson Oct. 21, 1930 1,584,976 Brunton May 13, 1926 2,387,012 Daugherty Oct. 16, 1945 FOREIGN PATENTS Number Country Date 562,562 Germany Oct. 27, 1932 501,426 Germany July 5, 1930 

